Implantable neurostimulation systems have proven therapeutic in a wide variety of diseases and disorders. These implantable neurostimulation systems typically include one or more stimulation leads implanted at the desired stimulation site and an implantable neurostimulator, such as an implantable pulse generator (IPG), implanted remotely from the stimulation site, but coupled either directly to the stimulation leads or indirectly to the stimulation leads via one or more lead extensions in cases where the length of the stimulation leads is insufficient to reach the IPG.
In the context of an SCS procedure, one or more stimulation leads are introduced through the patient's back into the epidural space under fluoroscopy, such that the electrodes carried by the leads are arranged in a desired pattern and spacing to create an electrode array. After proper placement of the stimulation leads at the target area of the spinal cord, the leads are anchored in place at an exit site to prevent movement of the stimulation leads. Whether lead extensions are used or not, the proximal ends of the stimulation leads exiting the spinal column are passed through a tunnel subcutaneously formed along the torso of the patient to a subcutaneous pocket (typically made in the patient's abdominal or buttock area) where a neurostimulator is implanted.
The stimulation leads are then connected directly to the neurostimulator by inserting the proximal ends of the stimulation leads within one or more connector ports of the IPG or connected to lead extensions, which are then inserted into the connector ports of the IPG. The IPG can then be operated to generate electrical pulses that are delivered, through the electrodes, to the targeted tissue, and in particular, the dorsal column and dorsal root fibers within the spinal cord.
Oftentimes, multiple lead bodies may extend from the spinal region of the patient. For example, multiple percutaneous leads may be implanted within the patient adjacent the spinal cord, or in the case of paddle leads, multiple lead tails may extend from the paddle, with each lead tail being coupled to specific electrodes on the paddle. Because the programming of the IPG will depend upon the physical locations of the electrodes relative to the patient's spinal cord, the proximal ends of the lead bodies are labeled before passing them through the tunneling straw, so that the surgeon can keep track of which set of electrodes is connected to which connector port on the implanted IPG (which may include up to four ports in the near future), or if multiple IPGs are to be implanted, which set of electrodes is connected to which IPG.
One technique used by surgeons to identify the lead bodies is to tie sutures around the proximal ends of the lead bodies prior to introducing them through the tunneling straw; for example, one suture around a first lead body, two sutures around a second lead body, three sutures around a third lead body, etc. Once the proximal ends of the lead bodies exit the tunneling straw, the surgeon can then identify each lead body (and thus the corresponding electrodes) by the number of sutures tied to the respective lead body, thereby allowing the lead body to be connected to the correct port on the IPG.
While this technique can be successfully employed to identify lead bodies, it considerably extends the length of the surgery time, which is undesirable. In some cases, the identification features, such as different colors or markings, can be incorporated into the proximal ends of the lead bodies, such that the lead bodies can be identified as they exit the tunneling straw. If the lead bodies are inserted into the incorrect connector ports, intra-operative testing of the lead placement may be compromised. Additional surgical time may be wasted to identify and correct the connection problem. If the errors remain unidentified, the patient may leave the operating room with the lead bodies incorrectly connected. During post-operative fitting, additional time may then be lost identifying and compensating for lead bodies that are not in the proper connector ports. This ultimately can result in sub-optimal therapy.